Fossils and Palaeontology
The Process of Fossilisation
once contained blood vessels, nerves etc, become filled
with minerals. There is also a process of replacement. This
is where the original minerals are replaced with different
minerals, but still keeping the exact original form of
the fossil. Most fossilised bones have undergone a
combination of both permineralisation and replacement.
The mineral that bones are made out of is called calciumsodium hydroxy apatite. This mineral, unfortunately,
weathers very easily. This means that when the process
of fossilisation is complete, it is very rare to find any of
this mineral remaining. In very rare cases, if the bone
comes into no contact with fluid from the time it is
buried until the time palaeontologists discover it, then
the bone stands a chance of being unaltered, but this
is very rare. Most bones go through a process called
permineralisation. Bones are porous, and the spaces that
Everything we know today about dinosaurs we have learned from the
fossilised remains that have been discovered. In fact, its the only reason we
even know dinosaurs existed! Fossils are the buried remains of organic life.
When a dinosaur dies, quite often the remains are
destroyed. They are can be eaten or destroyed by
weathering, where the minerals in the bones break down
and the bones fall apart and disintegrate. However, if
this process is prevented by a quick burial, the bones can
become fossilised.
However, as we mentioned earlier, bones are not the
only fossils we have discovered. Fossilised faeces have
been found, called coprolites, along with dinosaur eggs,
and most importantly we have also discovered trace
fossils. These are footprints and tracks left by dinosaurs.
These come in the form of molds, where there is an
impression left behind, or casts, where material has filled
the mold. These fossils tell us about how dinosaurs lived,
about their behaviour and can even tell the story of an
individual dinosaur.
In this magazine,
when we use the
term ‘Dinosaur’ we mean
non-avian dinosaurs (avian
means relating to birds), as
most specialists now agree
that birds are living
dinosaurs.
It has been 65 million years since Dinosaurs
last walked the Earth and so, as you can
imagine, most of the remains of dinosaurs
have long since been eaten or decomposed.
However, some remains have been fossilised
and these are what we have discovered. In
most fossils all of the soft tissues have long
gone, and usually it is the hard parts that
remain – for example bones and teeth.
Fossils are divided into two main types – trace
and body fossils. Body fossils include shells,
bones and other organic remains, whereas
trace fossils take the form of tracks, footprints
and other impressions (which are called mold
and cast fossils).
Most fossilisation involves replacement, where
the original body part is naturally replaced by
other minerals while buried.
6 | FUSE
Fossilisation Timeline
zz The animal dies or is killed and the body washes downstream
where it is rapidly buried. Any remaining flesh or soft tissues is
broken down by bacteria, le